Enhancing soluble factor from carrier-specific cells will be characterized. Physicochemical properties of this substance will be studied by density gradient ultracentrifugation, gel filtration and by electrofocusing. In order to see whether the soluble factor is antigen-T cell receptor complex, attempts will be made to stimulate T cells with carrier-coated insoluble material for the formation of enhancing soluble factor. In view of our previous findings that hapten-specific precursors (B cells) for IgG antibody are different from those involved in IgE antibody response, attempts will be made to stimulate B cells with anti-heavy chain to form anti-hapten antibodies. The possibility that T cells for IgA antibody response may be different from T cells for IgG antibody will be explored. IgA antibody response of mesenteric lymph node cells will be studied using similar experimental procedures to those employed to study IgG and IgE responses. The immunogenicity and carrier effect of modified antigen E will be studied in A/J strain of mice, using adoptive transfer technique.